Detailed studies will be made of the biosynthesis of the morphinan alkaloids in Papaver somniferum and Papaver bracteatum. Emphasis will be placed on learning the ultimate metabolic fate of these alkaloids and on studies with cell-free systems. Both agonists and antagonists of the morphinan group will be prepared, suitable modified for photoaffinity labeling of the mammalian CNS opiate receptors. These will be used in attempting to characterize the receptor proteins. Synthetic work will be directed to the total synthesis of thebaine and codeine, as well as to improve analgesics and improved analgesic antagonists.